11 



Mexican species: P. Ehrenbergiana, Haeinatochms ^fiisca , and.i:<?w- 

 arioidci, a few Indian species, as for instance P. Nepalensis and 

 P. atrosanguinea, and two species of the Southwestern United 

 States, viz. : 



PoTENTiLLA THURBERi A. Gray, Mem. Am. Acad. (II.) 5 : 318. 



1854. 



As described by Gray and Lehmann, P. Tlmrbcri should be per- 

 fectly green and only slightly hairy. Such specimens have been 

 collected as follows : 



New Mexico : Thurber, no. 1107, 185 i ; Dr. Henry, 1854; Dr. 

 Bigelow (Mex. Bound. Surv.), no. 347, 185 i ; E. L. Greene, 1880; 

 E. Palmer, 1869. Arir:ona : Lemmon, 1881 ; C. G. Pringle, 1884; 

 Wooton, 1895. 



More than half of the specimens in our collections that are 

 labelled /-*. TImrbeii do not agree with the original description, and 

 I take them to represent an undescribed species : 



POTENTILLA ATRORUBENS. 



Potentilla Thurbcri Rothrock, Wheeler Surv. 4 : 113. (mainly.) 



1878. 



Stem 4-7 dm. high, finely pubescent and with scattered long 

 villous spreading or reflexed hairs ; stipules ovate or lanceolate^ 

 1-2 cm. long, often toothed ; basal and lower stem-leaves long- 

 petioled, digitately 5-7-foliolate, glabrous or slightly silky above, 

 silky and white-tomentose beneath ; leaflets obovate to oblance- 

 olate, coarsely serrate; stem-leaves sessile, 3-5-foliolate ; cyme 

 open and branched; flowers about 15 mm. in diameter; calyx 

 silky-villous and finely pubescent, about i cm. in diameter ; bract- 

 lets lanceolate, often equalling the lanceolate-triangular, more or 

 less acuminate sepals ; petals dark reddish purple, very broadly 

 obcordate, exceeding the sepals ; stamens 20. (Plate 288.) 



This species much resembles P. TImrbeii, from which it has not 

 been distinguished. It differs, however, in several characters that 

 seem to be fairly constant, viz., the tomentum on the lower surface 

 of the leaves, the much sharper dentation, the long silky spread- 

 ing or reflexed hairs of the stem and calyx, and generally more 

 acuminate sepals. From the Mexican P.fnsca and P. coniarioides 

 it differs in the leaflets, which are serrate to the very base. It seems 

 to be more common than P. TImrbenz.n6. has about the same range. 



Arizona: Rothrock, no. 399, 1874; C. G. Pringle, no. 305, 

 1881 ; 1884; no. 1,578, 1887 ; M. E. Jones, 1884 ; J. G. Lemmon, 



